1. Field of the Invention
This invention relates to an ink jet recording apparatus, and more particularly, to the apparatus provided with an improved arrangement of signal input means.
2. Description of the Prior Art
Non-impact recording methods have recently drawn attention since noise upon recording is negligibly small. Among them, ink jet recording methods are known as a very powerful method. According to the ink jet recording method, a high speed recording is possible and furthermore, recording can be effected on ordinary papers without any special fixing treatment.
Ink jet recording method comprises projecting droplets of a recording liquid (ink) toward a record member. The ink jet recording methods are classified into several types based on the method of forming droplets and the method of controlling the projecting direction of the ink.
As energy sources for ejecting the recording liquid through an ejecting port (orifice), there may be used electrostatic attraction pressure change caused by mechanical vibration, pressure change caused by heat energy and the like.
One of representative ink jet recording methods is a continuous droplet ink jet system such as Sweet system (U.S. Pat. No. 3,596,275), Lewis and Brown system (U.S. Pat. No. 3,298,030) and the like. These systems comprise generating a liquid droplet stream having controlled charge amount by a means for generating continuous vibration, propelling the liquid droplets between deflection electrodes under a uniform electric field so as to control the trajectory of the liquid droplets, and projecting the liquid droplets toward a record member.
Another representative ink jet recording method is the ink-on-demand system such as Stemme system (U.S. Pat. No. 3,747,120) which comprises applying electric recording signals to a piezoelectric vibrator attached to a recording head having an orifice for ejecting a recording liquid (ink), changing the signals to the corresponding mechanical vibration of the piezoelectric vibrator and propelling ink droplets toward a record member by ejecting the droplets through the orifice when necessary.
A further ink jet recording system different from the above mentioned systems is that disclosed in Japanese Patent Application No. 118798/1977, and U.S. patent application Ser. No. 948,236 filed Oct. 3, 1978. This system comprises applying a thermal pulse as an information signal to a recording liquid introduced into a liquid chamber, causing the change of state of the liquid to produce an acting power, ejecting and propelling droplets of the recording liquid toward a record member.
According to the various systems above, there remain some technical problems to be solved.
One is to develop a recording apparatus containing ejecting orifices in a multi-array form so as to make a high speed recording by ink droplets. In this case, the apparatus is required to eject uniform ink droplets stably at a high density so as to improve quality of recorded letters and resolution.
The other is to produce a recording apparatus of high durability and provided with a minute structure of high precision.
However, it is not easy to satisfy such requirements for the apparatuses, especially from the manufacturing point of view. For example, a high technique is necessary to combine a plurality of nozzle portions each of which is made of a very small nozzle having a fine port so as to produce a recording apparatus of a multi-array since the nozzles are so minute. Moreover, it is required that each structure element is uniform and of high reliability and therefore, it is not easy to manufacture the recording apparatus in good yield.